Vertical cavity surface emitting lasers (VCSEL) typically include a first distributed Bragg reflector (DBR), also referred to as a mirror stack, formed on top of a substrate by semiconductor manufacturing techniques, an active region formed on top of the first mirror stack, and a second mirror stack formed on top of the active region. The VCSEL is driven by a current forced through the active region, typically achieved by providing a first contact on the reverse side of the substrate and a second contact on top of the second mirror stack.
Automatic power control (APC) of light emitting devices allows for a constant and a consistent output from these devices. Generally, automatic power control of edge emitting laser devices is easily achieved because edge emitting devices emit light from two ends. Thus, enabling one of the light emitting ends to be used to measure the power output, which is subsequently use to adjust the power input to the edge emitting device, thereby adjusting the power output.
However, automatic power control of a vertical cavity surface emitting laser (VCSEL) has typically been achieved through the use of optical devices, such as photodiodes or photodetectors, mirrors, beam splitters, and the like that are positioned manually in the optical path of the emission from the VCSEL. With the optical devices being positioned manually, several problems or disadvantages result, such as a high cost of manufacture, a lack of repeatability, and poor quality control.
Accordingly, it can be readily seen that conventional VCSELs and signal detection has several disadvantages and problems, thus not enabling their manufacture in a compact form. Therefore, a VCSEL device that includes a photodetector and method for making same that simplifies the fabrication process, reduces cost, and improves reliability would be highly desirable.
It is a purpose of the present invention to provide a new and improved VCSEL and photodetector device for automatic power control (APC) of the VCSEL emission.
It is another purpose of the present invention to provide a new and improved VCSEL and photodetector device which is simple and relatively inexpensive to manufacture.
It is still another purpose of the present invention to provide a new and improved VCSEL and photodetector device which is fabricated with a minimum of labor and cost.
It is a further purpose of the present invention to provide a new and improved VCSEL and photodetector device which can be utilized to control the output of the VCSEL.